Conservative Mark Harper says laws on non-EU workers will not be changed just so Domino’s Pizza can keep wages low.

The immigration minister, Mark Harper, has hit back at employers who say they have to recruit foreign workers from outside Europe to fill low-paid jobs by telling them they should offer better wages.

Harper said that Lance Batchelor, the chief executive of Domino’s Pizza, should reflect on the salaries he was offering if he could not fill 1,000 vacancies without recruiting unskilled staff from outside Europe.

The immigration minister told the Commons home affairs select committee: “He should probably pay his staff a little more and he might find them easier to recruit. It’s a market.”

Harper said that the government would not change the law to make it easier to recruit unskilled labour from outside Europe “just so he can keep his wages low”.

Batchelor complained earlier this week that his pizza takeaway and delivery chain was struggling to get enough employees, especially in London and the south-east.

“People who would have worked here a few years ago now don’t want these jobs. We could fill 1,000 jobs across the UK tomorrow if we could get candidates to apply for them,” he said.

Harper’s intervention came after the Home Office’s permanent secretary, Mark Sedwill, said Olympic-style preparations were being made at Britain’s borders in case of a possible surge in the arrival of Romanians and Bulgarians next month.

Sedwill told MPs that preparations, which include a sharper focus by Border Force officials, were being put in place in case there were “any surprises” when UK labour restrictions on migrants from both countries are lifted on 1 January.

Sedwill said that there was no official assessment of how many are expected to come, but said Britain was not the natural destination.

He said that, for example, there were hundreds of thousands of Romanian and Bulgarian migrants – if not a million – already living in Germany, but only 100,000 already living in Britain.

Harper said Romanians and Bulgarians had been able to live in Britain since 2007: “All we are talking about is that they no longer need to seek the permission of the Home Office before they come here to work.”

He said that estimates of how many would move to Britain were difficult because eight other EU countries were also lifting their restrictions on the access of Romanians and Bulgarians to their labour markets on 1 January. He said the variation in independent forecasts, ranging up to 350,000 over the next five years, illustrated how difficult it was to make an accurate estimate.

The Conservative immigration minister firmly slapped down the demand by more than 60 Tory backbenchers to extend the current restrictions on Romanians and Bulgarians beyond their 1 January expiry date.

The debate on the Tory backbenchers’ amendment to the current immigration bill has been postponed until after the Christmas recess.

Harper said an attempt to extend the seven-year transitional controls beyond their expiry date would be legally ineffective. It would require either an amendment to the European Union Act or changes to the Romanian and Bulgarian accession treaties, which would need the unanimous backing of all EU states, including Romania and Bulgaria.

The minister claimed, however, that there was growing support for Britain’s campaign to limit the abuse of the principle of free movement of labour within the EU, with 11 countries now backing Britain on the issue. The home secretary, Theresa May, has been pressing EU justice and home affairs ministers for the power to prevent benefit fraudsters and others who abuse freedom of movement returning to Britain once they have been excluded from the UK.

Harper also claimed to have drawn support from other EU states for tighter restrictions in the future on new accession states joining the EU. The current rules prescribe a seven-year transition period during which new EU citizens may travel to other countries, but are banned from working without permits or other restrictions.

The minister refused to comment on reports that Malta was now prepared to sell its passports, which give access to all EU countries to live and work, to any non-EU citizen willing to pay 650,000 euros (£540,000). He said that it was not for other EU member states or the European commission to interfere with national decisions on citizenship.